Recombinant polypeptides are sometimes expressed as fusions of individual domains or tags for functional or purification purposes. Recombinant DNA methods are traditionally used to join the sequences encoding each module, requiring a different construct for each combination. This poses a challenge to technologies involving expression of large protein collections composed of recurring modules joined in different combinations, as the number of constructs increases geometrically as a function of the number of modules used.
Although high-throughput systems for subcloning can handle large number of inserts in parallel, they are usually resource-intensive and generate a large number of constructs that are ultimately not necessary after initial characterization steps. Thus, there is an unmet need in the field for the development of a polypeptide expression system that allows for the modular expression and production of recombinant polypeptides.